THE UROGENITAL SYSTEM 



439 



but from the cloaca. The bladder anlage, however, is continued ventrally 

 as the allantoic stalk, which subsequently atrophies to form the middle 

 umbilical ligament. 



ventral 

 mesentery 



D. 



ght and left 

 coelom confluent 



-Diagrams illustrating the development of the mesonephros and gonadic 

 ridge. (From Patten's " Embryology of the Pig.") 



Reproductive Organs 



The human embryo is usually characterized as sexually indifferent. 

 This popular view is based upon the similarity of the anlagen of male and 

 female reproductive glands in the early embryo, and upon the occasional 

 appearance of hermaphroditic adult individuals. According to modern 

 genetical opinion, however, sex is definitely predetermined in the fertilized 



